FIG. 11 is a view showing an existing charge pump circuit for driving a video amplifier. The charge pump circuit shown is configured to be a circuit to be driven by a single power supply, which is a positive power supply. Such a charge pump circuit is disclosed by, for example, Patent Document 1.
The existing charge pump circuit shown in FIG. 11 generates a negative power-supply voltage (VEE) with a positive power-supply voltage (VDD) supplied from a positive power supply and ground voltage (GND). Then, a driven circuit to be driven between the positive power-supply voltage and the negative power-supply voltage directly drives a load without the use of a capacitor for cutting DC (Direct Current) with the ground voltage set as a center level, and outputs signals. In such a charge pump circuit, switching elements 111 and 113 are switched on in a first period of a clock signal, and a capacitor C1 is directly connected between the supplied positive voltage and the ground voltage. In this situation, electric charge is accumulated in the capacitor C1.
In addition, in a second period of the clock signal, the switching elements 111 and 113 are switched off, and simultaneously switching elements 112 and 114 are switched on. In this situation, a capacitor C2 is directly connected between a negative voltage terminal for generating the negative voltage and the ground voltage, and the accumulated electric charge is transferred. The charge pump circuit shown in FIG. 11 repeatedly performs a series of operations as described above to generate the negative voltage.